The invention concerns a measuring transformer for a gas-insulated or liquid-insulated high-voltage switching installation with metal encapsulation, carrying several conductors.
From Deutsche Offenlegungsschrift 2,125,297 which corresponds to U.S. Pat. No. 3,763,378, a measuring transformer is known with which a current and voltage measurement in a single-phase high-voltage switching installation can be performed. Within the metal encapsulation of the high-voltage switching installation, this measuring transformer includes an insulator which carries a conducting layer on its inside surface facing the high-voltage conductor. The insulator contains a current transformer core with a system of secondary windings mounted on it. In this measuring transformer, the conducting layer forms a surface-type electrode which, in cooperation with the high-voltage conductor surrounded by it, forms the high-potential capacitor of a capacitive voltage divider. The low-potential capacitor, followed by an amplifier, is located outside the metal encapsulation. The known measuring transformer is suited for the measurement of current and voltage in single-phase high-voltage switching installations and cannot be used in high-voltage switching installations carrying several conductors.